1. Field of the Invention
The present invention relates to tentacle-like manipulators which can bend in at least one plane and which can extend and contract in length.
2. Description of Related Art
Prior art tentacle-like manipulators are disclosed in U.S. Pat. No. 3,060,972 issued Oct. 30, 1962 to Gilbert J. Sheldon for a flexible tube structure of fixed length with opposing cables used to flex the structure; U.S. Pat. No. 3,497,083 issued Feb. 24, 1970 to Victor C. Anderson for a tensor arm manipulator of fixed length comprised of universal joints on pivoting plates with a plurality of tendons connected to selected plates; U.S. Pat. No. 4,393,728 issued Jul. 19, 1983 to Ove Larson and Charles Davidson for a flexible robot arm with stacked convex disks with tendons to control bending; and U.S. Pat. 4,551,061 issued Nov. 5, 1985 to Ralph W. Olenick for a flexible, extensible robot arm with three elastomeric tubes to control extension and bending and rods sense the arm length and curvature.
All of the above-mentioned prior patents disclose variations on tentacle-like manipulator designs which employ multiple joints or segments to approximate continuous curvature of the arm, and which employ cables or differential expansion of tubes to effect bending of the arm.
The important characteristics of tentacle manipulators include strength-to-weight ratio; ability to extend or contract in length (and percent extension/contraction); ability to bend in any direction with controlled curvature; ability to control the radius of bending; ability to allow two or more regions of bending along the length of the arm; provision for varying the compliance (mechanical impedance) of the arm and simplicity of actuation means.